Encapsulated proppants

ABSTRACT

A capsule for carrying a proppant for emplaced in a formation containing formation fluid by a hydraulic fracture operation using a fracturing fluid. The capsule includes a capsule body. The capsule body includes a proppant. There is a surface layer on the capsule body that is permeable to the formation fluid or the fracturing fluid or is permeable to both the formation fluid and the fracturing fluid. The proppant material is dry cement that interacts with the formation fluid or the fracturing fluid or both the formation fluid and the fracturing fluid that migrate through the surface layer and is taken up by the dry cement causing the dry cement to harden.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Division of application Ser. No. 14/148,602filed Jan. 6, 2014, which claims benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 61/781,789 filed Mar. 14, 2013entitled “Encapsulate Proppants,” the disclosure of which is herebyincorporated by reference in its entirety for all purposes.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

The United States Government has rights in this invention pursuant toContract No. DE-AC52-07NA27344 between the United States Department ofEnergy and Lawrence Livermore National Security, LLC for the operationof Lawrence Livermore National Laboratory.

BACKGROUND

Field of Endeavor

The present application relates to proppants for hydraulic fracturingand more particularly to encapsulated proppants for hydraulicfracturing.

State of Technology

Hydrofracturing for oil, gas, and geothermal recovery is in wide useparticularly for low permeability reservoirs such as shales. In thesecases, large hydraulic pressure is applied to a rock to cause a fractureto penetrate the rock, allowing access to extract the heat, oil, or gas.The fracture typically would close on it's own after the release of thehydraulic pressure pulse, and must be “propped” with a granular materialthat holds the fracture open.

The transport of proppant to the relatively small fracture is a keyissue in designing hydraulic fractures. The proppant must fill thefracture (appropriately sized), it must hold the fracture open (strongenough), and it must not generate additional fine material eitherthrough damaging the rock, or by breaking down itself (the fine materialcan block flow). These properties typically require material such asvery-well-rounded sand, epoxy coated sands, or even sintered ceramics tobe used as proppant. All of these materials, however, are relativelydense, and typically get more dense as more strength is required. Thatdensity requires the fracturing fluid to be very viscous in order totransport the proppant completely into the fracture, and typically aconsiderable excess of water is used to fully drive the proppant to thefracture limits. The highly altered chemistry (for viscosity) and theexcess amounts lead to increased expense in fracturing operations, andcause many of the observed environmental issues in shale gas fracturingoperations.

Applicants have develop technology for carbon dioxide capture thatencapsulates a reactive chemical (in that case a solvent) within apermeable polymer shell that keeps the reactive chemical encapsulated,while permitting some reactants (water and carbon dioxide) to passthrough and enter the solvent. The present invention uses that samebasic technology to encapsulate the reactive chemicals for creating astrong proppant, keeping them from reacting until the appropriate time.The silicone-based capsules already tested will be appropriate forproppant use, as they are strong, non-reactive, and allow waterpermeation required to initiate hardening of the reactive proppantprecursors carried inside.

SUMMARY

Features and advantages of the present invention will become apparentfrom the following description. Applicants are providing thisdescription, which includes drawings and examples of specificembodiments, to give a broad representation of the invention. Variouschanges and modifications within the spirit and scope of the inventionwill become apparent to those skilled in the art from this descriptionand by practice of the invention. The scope of the invention is notintended to be limited to the particular forms disclosed and theinvention covers all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theclaims.

The present invention provides improved proppants for hydraulicfracturing in oil, gas, and geothermal operations created byencapsulating reactive materials such as cements in a polymer casingdesigned to allow water to enter the capsule after a defined length oftime or upon temperature increase. In a preferred embodiment the capsuleis typically 0.5 to 2 mm in diameter, similar in size to currentproppant materials.

In one embodiment, the present invention provides a capsule for carryinga proppant for emplacement in a formation containing a formation fluidby a hydraulic fracture operation using a fracturing fluid. The capsuleincludes a capsule body. The capsule body includes a proppant. There isa surface layer on the capsule body that is permeable to the formationfluid or the fracturing fluid or is permeable to both the formationfluid and the fracturing fluid. In one embodiment, the proppant materialis dry cement that interacts with the formation fluid or the fracturingfluid or both the formation fluid and the fracturing fluid that migratethrough the surface layer and is taken up by the dry cement causing thedry cement to harden.

Advantages of the present invention include, the ability for theencapsulated proppant to expand upon reaction, allowing more completepropping of the fracture. The density of proppant capsules can also beadjusted both by material choice, and by deliberate addition of voidspace within the capsule. Lower density proppant permits much widerchoice of fracturing fluid chemistries, use of less fracturing water,and easier reuse or recycling of fracturing water by reducing the needto add viscosifiers to the water.

Capsules can be made any size as fitted to formation and fracture.Reaction rate can be adjusted by polymer choice, granularity of reactivematerial, or polymer thickness. Reactive material such as cements may besolid, powdered solid, powder in a liquid such as alcohol, or reactiveliquids; or combinations of those. Cements typically used for wellconstruction can be used to ensure appropriate properties. The presentinvention has many uses, for example the present invention has use inhydraulic fracturing for enhanced oil, gas and geothermal recovery andshale gas fracturing.

The invention is susceptible to modifications and alternative forms.Specific embodiments are shown by way of example. It is to be understoodthat the invention is not limited to the particular forms disclosed. Theinvention covers all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of the specification, illustrate specific embodiments of theinvention and, together with the general description of the inventiongiven above, and the detailed description of the specific embodiments,serve to explain the principles of the invention.

FIGS. 1A and 1B illustrate one embodiment of the encapsulated proppantof the present invention.

FIGS. 2A and 2B show the encapsulated proppants of the present inventionpositioned in a fracture.

FIGS. 3A, 3B, and 3C illustrate another embodiment of the encapsulatedproppant of the present invention.

FIGS. 4A, 4B, and 4C illustrate yet another embodiment of theencapsulated proppant of the present invention.

FIG. 5 illustrates a capsule making system.

FIGS. 6A and 6B are additional illustrations that show additionalfeatures of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the drawings, to the following detailed description, and toincorporated materials, detailed information about the invention isprovided including the description of specific embodiments. The detaileddescription serves to explain the principles of the invention. Theinvention is susceptible to modifications and alternative forms. Theinvention is not limited to the particular forms disclosed. Theinvention covers all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theclaims.

The present invention provides encapsulation to carry a package ofchemicals as it is emplaced during a hydraulic fracture operation andthe creation and maintenance of a fracture. The encapsulated package ofchemicals reacts, either due to time passing and the diffusion of waterthrough the polymer shell, or the presence of heat at depth in theearth.

Some of the major advantages of the present invention over conventionalpackages of chemicals for fracturing are: (1) the ability to adjust thedensity of the proppant of the present invention to improve fracturingfluid composition and maximize proppant placement with minimum waterusage; (2) expansion of the proppant during emplacement to improvefracture opening; (3) adaptation of the shape of the proppant duringhardening to the shape of the formation it touches, maximizing footprintand minimizing formation damage; and (4) the ability to adjust theexterior coat of the capsule to improve interactions with thehydrofracturing fluid and minimize reactions with the formation rock.

Referring now to the drawings and in particular to FIGS. 1A and 1B oneembodiment of the encapsulated proppant of the present invention isillustrated. The encapsulated proppant is designated generally by thereference numeral 100. The encapsulated proppant 100 includes a capsulebody 104 with a surface layer 102 on the capsule body 104. FIG. 1Aillustrates the encapsulated proppant 100 prior to its introduction intothe formation during a hydraulic fracturing operation. FIG. 1Billustrates the encapsulated proppant 100 after its introduction intothe formation during a hydraulic fracturing operation.

As shown in FIG. 1A the surface layer 102 can be a polymer shell, forexample silicone or norton optical adhesive. The capsule body 104 can bedry premixed cement. In one embodiment the capsule body 104 constitutesa reactive material that is held inside a slightly elastic polymer shell102. Diffusion of water through the shell 102 initiates and/or completesthe reaction of the material 104 to form a hard, strong proppant sphere.In use in hydrofracturing the polymer shell 102 can deform as the insidematerial hardens minimizing damage to the formation as the walls of thefracture close on the proppant spheres.

Referring now to FIG. 1B, the encapsulated proppant 100 is illustratedafter its introduction into the formation during a hydraulic fracturingoperation. The polymer shell 102 is still largely intact. The cement 104has hardened through reaction with water (the formation fluid or thefracturing fluid or both the formation fluid and the fracturing fluid)diffusing through the polymer shell 102. The cement 104 continues toharden with time. The reaction rate is designed through control of drychemistry and polymer shell properties.

The structure of the encapsulated proppant 100 having been described,the making of the encapsulated proppant 100 will now be considered. Atypical way to create them is to encapsulate a cement used for wellboreconstruction, and whose properties are well known as a function ofpressure, temperature, and water chemistry. These cements are typicallyin powdered form, so it may be necessary to suspend them in asacrificial liquid during the encapsulation process. A volatile organicfluid such as an alcohol (methanol, ethanol for instance) could be usedfor this purpose. The sacrificial liquid would then be evaporatedthrough the capsule wall in a preparation step prior to use of theproppant. The final version would have little or no liquid remaininginside, with mostly dry cement powder and some residual liquid.

Other forms of reactive material 104 could be used inside the capsules100, provided they harden by reaction with water. This is necessary inorder to add mass to the proppant as it reacts, allowing additionalstrength and volume without the burden of carrying all of the necessarychemicals inside the capsule. By only having some of the components ofthe final reacted proppant within the original capsule, the overall sizeand density of the capsule can be limited. This improves the placementof the proppant and permits less total water usage in hydrofracturing.Some forms of liquid cement could be used as well. Reactive materialthat reacts with water and foams slightly as it hardens, such aspolyurethane glue (diphenylmethane diisocyanate) can permit an increasein volume while retaining most of the material's strength.

Referring now to FIGS. 2A and 2B an illustration shows the encapsulatedproppants of the present invention positioned in a fracture. Theencapsulated proppants in the fracture are designated generally by thereference numeral 200.

As illustrated in FIG. 2A, the individual encapsulated proppants 206 areintroduced into the formation 204 during a hydraulic fracturingoperation and lodged in a fracture 202. The fracture 202 closes andcontacts the capsules 206 with a minor deformation in the formation 204.The deformation is illustrated by the reference numeral 208.

Referring now to FIG. 2B, one of the individual encapsulated proppants206 after the fracture 202 closes and contacts the capsules 206 with thepolymer shell 212 slightly deformed as designated by the arrow 210. Thepolymer shell 202 is still largely intact. The cement 214 has hardenedthrough reaction with water (the formation fluid or the fracturing fluidor both the formation fluid and the fracturing fluid) diffusing throughthe polymer shell 202. The cement 214 continues to harden with time. Thereaction rate is designed through control of dry chemistry and polymershell properties. There has been no creation of fines due toencapsulation of the cement 214 and the relatively soft polymer shell212 has deforming slightly.

Referring now to FIGS. 3A, 3B, and 3C another embodiment of theencapsulated proppant of the present invention is illustrated. Thisembodiment of the encapsulated proppant of the present inventionprovides an expanding reactive proppant. The encapsulated expandingreactive proppant is designated generally by the reference numeral 300.The expanding reactive proppant proppant 300 includes a capsule body 304with a surface layer 302 on the capsule body 304. FIG. 3A illustratesthe encapsulated expanding reactive proppant 300 prior to itsintroduction into the formation during a hydraulic fracturing operation.FIG. 3B illustrates the encapsulated expanding reactive proppant 300after its introduction into the formation during a hydraulic fracturingoperation.

As shown in FIG. 3A the surface layer 302 can be a polymer shell, forexample silicone or norton optical adhesive. The capsule body 304 can bedry premixed cement with expanding properties. In one embodiment thecapsule body 304 constitutes a reactive material that is held inside aslightly elastic polymer shell 302. Diffusion of water through the shell302 initiates and/or completes the reaction of the material 304 to forma hard, strong, expanded proppant sphere. In use in hydrofracturing thepolymer shell 302 can deform as the inside material hardens minimizingdamage to the formation as the walls of the fracture close on theproppant spheres.

Referring now to FIG. 3B, the encapsulated proppant 300 is illustratedafter its introduction into the formation during a hydraulic fracturingoperation. The capsule body 304 has an overall volume increased by up to50%. The polymer shell 302 is still largely intact but has thinned. Thecement 304 has hardened through reaction with water (the formation fluidor the fracturing fluid or both the formation fluid and the fracturingfluid) diffusing through the polymer shell 302. The cement 304 continuesto harden with time. The reaction rate is designed through control ofdry chemistry and polymer shell properties. The additional mass andvolume in the capsule body 302 has come through reaction with water (theformation fluid or the fracturing fluid or both the formation fluid andthe fracturing fluid) diffusing through the polymer shell 302.

Referring now to FIG. 3C, the expanding reactive proppants 306 are shownin place in the fracture 312 in the formation 310. The encapsulatedexpanding reactive proppants 306 are shown after the fracture 312 closesand contacts the capsules 306 with the polymer shell 302 slightlydeformed. The deformation is illustrated by the reference numeral 308.The capsules 312 have expanded to meet the fracture 312 at maximum widthduring fracture formation. The capsules 312 “barrel” slightly as theyexpand and harden, increasing contact footprint and decreasing formationdamage. A smaller total proppant count in the fracture 312 keepspermeability high. The polymer shells 302 are still largely intact. Thecement 306 has hardened through reaction with water (the formation fluidor the fracturing fluid or both the formation fluid and the fracturingfluid) diffusing through the polymer shell 302. The cement 306 continuesto harden with time. The reaction rate is designed through control ofdry chemistry and polymer shell properties.

Referring now to FIGS. 4A, 4B, and 4C another embodiment of theencapsulated proppant of the present invention is illustrated. Thisembodiment of the encapsulated proppant of the present inventionprovides an expanding reactive proppant containing hollow vesicles. Theencapsulated expanding reactive proppant is designated generally by thereference numeral 400. The expanding reactive proppant proppant 400includes a capsule body 404 with a surface layer 402 on the capsule body404. FIG. 4A illustrates the encapsulated expanding reactive proppant400 prior to its introduction into the formation during a hydraulicfracturing operation. FIGS. 4B and 4C illustrate the encapsulatedexpanding reactive proppants 400 after their introduction into theformation during a hydraulic fracturing operation.

As shown in FIG. 4A the surface layer 402 can be a polymer shell, forexample silicone or norton optical adhesive. The capsule body 404 can bedry premixed cement with expanding properties. Hollow vesicles 406 arecontained in the dry premixed cement. The hollow vesicles 406 aresimilar to the outside polymer shell 402. The Bulk density is reduced bythe volume of the hollow vesicles. In one embodiment the capsule body404 constitutes a reactive material that is held inside a slightlyelastic polymer shell 402. Diffusion of water through the shell 402initiates and/or completes the reaction of the material 404 to form ahard, strong, expanded proppant sphere. In use in hydrofracturing thepolymer shell 402 can deform as the inside material hardens minimizingdamage to the formation as the walls of the fracture close on theproppant spheres.

Referring now to FIG. 4B, the encapsulated proppant 400 is illustratedafter its introduction into the formation during a hydraulic fracturingoperation. The capsule body 404 has an overall volume increased by up to50%. The polymer shell 402 is still largely intact but has thinned. Theinternal hollow vesicles 406 are intact but have decreased in size. Thecement 404 has hardened through reaction with water (the formation fluidor the fracturing fluid or both the formation fluid and the fracturingfluid) diffusing through the polymer shell 402. The hardened proppant400 maintains full strength due to the spherical shape of the hollowvesicles 406. The cement 404 continues to harden with time. The reactionrate is designed through control of dry chemistry and polymer shellproperties. The additional mass and volume in the capsule body 402 hascome through reaction with water (the formation fluid or the fracturingfluid or both the formation fluid and the fracturing fluid) diffusingthrough the polymer shell 402.

Referring now to FIG. 4C, the lower density proppants 406 are shown inplace in the fracture 412 in the formation 310. The behavior of thelower density proppants 406 after emplacement is similar to the normaldensity proppants; however, the lower density proppants 406 are mucheasier to place into the fracture 412 due to lowered density. Theencapsulated lower density proppants 406 are shown after the fracture402 closes and contacts the capsules 406 with the polymer shell 408slightly deformed. The deformation is illustrated by the referencenumeral 408. The capsules 406 have expanded to meet the fracture 412 atmaximum width during fracture formation. The capsules 406 “barrel”slightly as they expand and harden, increasing contact footprint anddecreasing formation damage. A smaller total proppant count in thefracture 412 keeps permeability high. The polymer shells 402 are stilllargely intact. The cement 406 has hardened through reaction with water(the formation fluid or the fracturing fluid or both the formation fluidand the fracturing fluid) diffusing through the polymer shell 408. Thecement 406 continues to harden with time. The reaction rate is designedthrough control of dry chemistry and polymer shell properties.

Referring now to FIG. 5 a system for making microcapsules containingproppant material is illustrated. The system for making encapsulatedproppant material is designated generally by the reference numeral 500.The schematically illustrated system 500 includes the following items:an injection tube 504, a collection tube 520, and an outer tube 518.

In operation the inner fluid 502 flows in the injection tube 504. Asthis fluid 502 proceeds it passes thru a droplet forming nozzle 506 atthe end of injection tube 504 within the end portion 510 of the outertube 518. The formed droplet 514 is released from the nozzle and becomesencased in the middle fluid 516, the middle fluid 516 is flowing in thedirection indicated by the arrows 512. The droplet 514 in the middlefluid 516 becomes encased in fluid 508 forming encapsulatedmicrocapsules 514 that have proppant material in a core with a thinouter shell. The above described method will produce encapsulated cementmaterial of a controlled size enclosed in a shell.

Systems for producing microcapsules are described in U.S. Pat. No.7,776,927 and in U.S. Published Patent Application Nos. 2009/0012187 and2009/0131543. U.S. Pat. No. 7,776,927 to Liang-Yin Chu et al, assignedto the President and Fellows of Harvard College, discloses emulsions andthe production of emulsions, including multiple emulsions andmicrofluidic systems for producing multiple emulsions. A multipleemulsion generally describes larger droplets that contain one or moresmaller droplets therein which, in some cases, can contain even smallerdroplets therein, etc. Emulsions, including multiple emulsions, can beformed in certain embodiments with generally precise repeatability, andcan be tailored to include any number of inner droplets, in any desirednesting arrangement, within a single outer droplet. In addition, in someaspects of the invention, one or more droplets may be controllablyreleased from a surrounding droplet. U.S. Published Patent ApplicationNo. 2009/0012187 to Liang-Yin Chu et al, assigned to the President andFellows of Harvard College, discloses multiple emulsions, and to methodsand apparatuses for making emulsions, and techniques for using the same.A multiple emulsion generally describes larger droplets that contain oneor more smaller droplets therein which, in some cases, can contain evensmaller droplets therein, etc. Emulsions, including multiple emulsions,can be formed in certain embodiments with generally preciserepeatability, and can be tailored to include any number of innerdroplets, in any desired nesting arrangement, within a single outerdroplet. In addition, in some aspects of the invention, one or moredroplets may be controllably released from a surrounding droplet. U.S.Published Patent Application No. 2009/0131543 to David A. Weitzdiscloses multiple emulsions, and to methods and apparatuses for makingmultiple emulsions. A multiple emulsion, as used herein, describeslarger droplets that contain one or more smaller droplets therein. Thelarger droplet or droplets may be suspended in a third fluid in somecases. In certain embodiments, emulsion degrees of nesting within themultiple emulsion are possible. For example, an emulsion may containdroplets containing smaller droplets therein, where at least some of thesmaller droplets contain even smaller droplets therein, etc. Multipleemulsions can be useful for encapsulating species such as pharmaceuticalagents, cells, chemicals, or the like. In some cases, one or more of thedroplets (e.g., an inner droplet and/or an outer droplet) can changeform, for instance, to become solidified to form a microcapsule, a liposome, a polymero some, or a colloid some. As described below, multipleemulsions can be formed in one step in certain embodiments, withgenerally precise repeatability, and can be tailored to include one,two, three, or more inner droplets within a single outer droplet (whichdroplets may all be nested in some cases). As used herein, the term“fluid” generally means a material in a liquid or gaseous state. Fluids,however, may also contain solids, such as suspended or colloidalparticles. U.S. Pat. No. 7,776,927 and U.S. Published Patent ApplicationNos. 2009/0012187 and 2009/0131543 are incorporated herein by thisreference.

The present invention provides benefits in fabrication andmanufacturability. The encapsulated cement material can be fabricated ata size small enough for efficient mass transfer and large enough forease of handling. The present invention provides methods to fabricatecement material filled shells. The present invention provides benefitsin survivability and robustness.

Referring now to FIGS. 6A and 6B additional illustrations of theencapsulated proppant of the present invention are provided to furtherillustrate the present invention. The additional illustrations of theproppant are designated generally by the reference numeral 600. Theencapsulated proppant 600 includes a capsule body 604 with a surfacelayer 602 on the capsule body 604. FIG. 6A illustrates the encapsulatedproppant 600 after its introduction into the formation during ahydraulic fracturing operation. FIG. 6B illustrates the encapsulatedproppant 600 in the formation during a hydraulic fracturing operation.

As illustrated in FIG. 6A the surface layer 602 can be a polymer shell,for example silicone or norton optical adhesive. The capsule body 604can be dry premixed cement. In one embodiment the capsule body 604constitutes a reactive material that is held inside a slightly elasticpolymer shell 602. Diffusion of water through the shell 602 asillustrated by the arrows 606 initiates and/or completes the reaction ofthe material 604 to form a hard, strong proppant sphere. In use inhydrofracturing the polymer shell 602 can deform as the inside materialhardens minimizing damage to the formation as the walls of the fractureclose on the proppant spheres.

As illustrated in FIG. 6B, the encapsulated proppant 600 is shown afterits introduction into the formation during a hydraulic fracturingoperation. The polymer shell 602 is still largely intact. The cement 604has hardened through reaction with water (the formation fluid or thefracturing fluid or both the formation fluid and the fracturing fluid)diffusing through the polymer shell 602. The cement 604 continues toharden with time. The reaction rate is designed through control of drychemistry and polymer shell properties.

Other forms of reactive material 604 could be used inside the capsule600, provided they harden by reaction with water. This is necessary inorder to add mass to the proppant as it reacts, allowing additionalstrength and volume without the burden of carrying all of the necessarychemicals inside the capsule. By only having some of the components ofthe final reacted proppant within the original capsule, the overall sizeand density of the capsule can be limited. This improves the placementof the proppant and permits less total water usage in hydrofracturing.Some forms of liquid cement could be used as well. Reactive materialthat reacts with water and foams slightly as it hardens, such aspolyurethane glue (diphenylmethane diisocyanate) can permit an increasein volume while retaining most of the material's strength.

Although the description above contains many details and specifics,these should not be construed as limiting the scope of the invention butas merely providing illustrations of some of the presently preferredembodiments of this invention. Other implementations, enhancements andvariations can be made based on what is described and illustrated inthis patent document. The features of the embodiments described hereinmay be combined in all possible combinations of methods, apparatus,modules, systems, and computer program products. Certain features thatare described in this patent document in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.Moreover, the separation of various system components in the embodimentsdescribed above should not be understood as requiring such separation inall embodiments.

Therefore, it will be appreciated that the scope of the presentinvention fully encompasses other embodiments which may become obviousto those skilled in the art. In the claims, reference to an element inthe singular is not intended to mean “one and only one” unlessexplicitly so stated, but rather “one or more.” All structural andfunctional equivalents to the elements of the above-described preferredembodiment that are known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the present claims. Moreover, it is not necessary for adevice to address each and every problem sought to be solved by thepresent invention, for it to be encompassed by the present claims.Furthermore, no element or component in the present disclosure isintended to be dedicated to the public regardless of whether the elementor component is explicitly recited in the claims. No claim elementherein is to be construed under the provisions of 35 U.S.C. 112, sixthparagraph, unless the element is expressly recited using the phrase“means for.”

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. An apparatus that is introduced into aformation containing formation fluid during a hydraulic fractureoperation wherein the hydraulic fracturing operation has a fracturingfluid wherein the formation has a fracture that closes after thehydraulic fracturing operation, comprising: a spherical capsule adaptedto be positioned in the fracture and remain in the fracture when thefracture closes; said spherical capsule having a spherical capsule body,a spherical surface layer on said spherical capsule body wherein saidspherical surface layer is a solid polymer shell made of a permeablepolymer material that is permeable to the formation fluid or thefracturing fluid or is permeable to both the formation fluid and thefracturing fluid wherein said spherical permeable surface layer enablesfluid to migrate through said spherical permeable surface layer, andwherein said permeable polymer material is an elastic polymer materialthat is adapted to deform when said spherical capsule is positioned inthe fracture and remains in the fracture when the fracture closes; aproppant encapsulated within said spherical permeable surface layer,wherein said proppant is made of a dry premixed cement proppant materialthat interacts with the formation fluid or the fracturing fluid or boththe formation fluid and the fracturing fluid that migrates through saidspherical permeable surface layer and initiates a reaction with said drypremixed cement proppant material causing said proppant material toharden; and hollow vesicles encapsulated within said spherical permeablesurface layer together with said dry premixed cement proppant materialwherein said hollow vesicles are made of said elastic polymer materialthat is adapted to deform when said spherical capsule and said hollowvesicles are positioned in the fracture and remain in the fracture whenthe fracture closes.
 2. The apparatus of claim 1 wherein said hollowvesicles have an outer portion made of said elastic polymer material andan inner hollow portion and wherein said hollow vesicles have an initialsize when said hollow vesicles are positioned in the fracture and saidhollow vesicles have a smaller size when the fracture closes.
 3. Theapparatus of claim 1 wherein said surface layer is made of silicone. 4.The apparatus of claim 1 wherein said dry premixed cement proppantmaterial is adapted to harden when the formation fluid or the fracturingfluid or both the formation fluid and the fracturing fluid migratesthrough said spherical permeable surface layer and wherein said hollowvesicles within said proppant have an initial size when said hollowvesicles are positioned in the fracture and said hollow vesicles have asmaller size when the fracture closes.